Integrated process for the production of biofuels from solid urban waste

ABSTRACT

Integrated process for the production of biofuels from solid urban waste which comprises:
         subjecting said waste to liquefaction obtaining a mixture comprising an oily phase consisting of bio-oil, a solid phase and an aqueous phase;   subjecting the mixture obtained from said liquefaction to separation obtaining an oily phase consisting of bio-oil, a solid phase and an aqueous phase;   subjecting the oily phase consisting of bio-oil, obtained from said separation to hydroconversion in slurry phase, in the presence of at least one nanodispersed hydrogenation catalyst;   wherein said liquefaction is carried out at a temperature ranging from 150° C. to 350° C., preferably ranging from 200° C. to 320° C., at a pressure ranging from 5 bar to 170 bar, preferably ranging from 15 to 115 bar and for a time ranging from 5 minutes to 240 minutes, preferably ranging from 15 to 90 minutes.       

     The biofuels thus obtained can be used as such, or in a mixture with other fuels, for automotive.

SUMMARY

The present invention relates to an integrated process for theproduction of biofuels from solid urban waste.

More specifically, the present invention relates to an integratedprocess for the production of biofuels from solid urban waste whichcomprises subjecting said waste to liquefaction, separating the oilyphase consisting of bio-oil obtained from said liquefaction andsubjecting said oily phase consisting of bio-oil to hydroconversion inslurry phase in the presence of at least one nanodispersed hydrogenationcatalyst.

BACKGROUND

The biofuels thus obtained can be used as such, or in a mixture withother fuels, for automotive.

As a result of the decrease in fuel reserves of a fossil origin and ofthe negative impact on the environment produced by anthropic emissionsof carbon dioxide (CO₂), all studies directed towards the production ofbiofuels and allowing, in the long run, complete transition to renewableenergy vectors, are becoming of increasing importance. Among the newsustainable energy sources, biomasses can significantly contribute toachieving these objectives.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing the process of turning solid urban wasteinto biofuel.

DETAILED DESCRIPTION

Solid urban waste, for example, in particular of an organic origin,represents a potential raw material for the production of liquid fuels.Four types of waste can be mainly associated with this category:

-   -   the organic fraction of solid urban waste deriving from selected        collection;    -   pruning deriving from the maintenance of public parks;    -   agribusiness waste products and waste products of large        retailers;    -   primary and biological sludges produced by urban water treatment        plants.

Most of these materials are currently disposed of in landfills or sentto composting, and/or incineration, and/or anaerobic digestion plants.

Alternatively, solid urban waste could be used as raw material in aliquefaction process (thermal treatment carried out on wet biomasses)for the production of bio-oil to be sent to a subsequent refinery step(upgrading) for the production of biofuels for automotive. Due to thehigh content of oxygen or of other heteroatoms, in fact, bio-oil is notsuitable for being used either as such as fuel for automotive, or mixedwith other fuels for automotive. The removal of hetero-elements, themaximization of the yield to liquid products of a hydrocarbon typewithin the correct distillation range, the correspondence with thespecifications and the regulations for automotive fuels, areconsequently the primary objective of upgrading processes for theproduction of biofuels. The upgrading of bio-oil can be carried out, forexample, through thermal pyrolysis or cracking processes, or throughhydrotreatment, and/or hydrocracking and/or hydroisomerizationprocesses.

It should also be taken into account that solid urban waste is alsoconsidered an optimum raw material for producing biofuels as this rawmaterial does not have to be produced but, on the contrary, has alreadybeen collected and localized in medium/large storage centres.Furthermore, this raw material is obviously not in conflict withagri-food cycles, as is the case on the contrary, with many otherbiomasses normally used as renewable energy sources.

Efforts have been made in the art to utilize urban and/or industrialand/or agricultural waste and/or residues, for energy purposes.

American patent U.S. Pat. No. 4,618,736, for example, describes aprocess for producing hydrocarbons from a cellulose material comprisingthe following steps: forming a suspension of the cellulose material in apolycyclic liquid hydrogen-donor compound, said suspension containing aquantity of water equal to at least 5% by weight, but not more thanapproximately 10% by weight, with respect to the weight of the cellulosematerial; subjecting the suspension to a temperature higher than 200° C.and to an increasing pressure up to at least 1000 psi, in the presenceof hydrogen, in order to obtain the hydrogenation of the cellulosematerial and to produce a mixture of gaseous, liquid and solidhydrocarbons, having an oxygen content lower than 10% by weight and acalorific power of over 15000 Btu/Ib; separating the mixture ofhydrocarbons into three phases: gaseous, liquid and solid; recoveringsaid polycyclic liquid hydrogen-donor compound from the liquid phase andrecycling it to the treatment of cellulose material. Said cellulosematerial can derive from domestic or urban waste or from vegetables.Said polycyclic liquid hydrogen-donor compound is preferably tetralin.

American patent U.S. Pat. No. 4,670,613 describes a process for theproduction of liquid products containing hydrocarbons which essentiallyconsists in introducing a biomass into a reaction area, in the presenceof water, at a pressure higher than the partial pressure of the watervapour and at a temperature of at least 300° C., leaving said biomass inthe reaction area for more than 30 seconds; separating the solidproducts from the fluid leaving the reaction area and maintaining thefluid remaining in said area in a single phase; subsequently separatingthe liquid products from the remaining fluid. Said biomass can beselected from a wide range of biomasses of different origins such as,for example, biomasses of a vegetable origin, biomasses deriving fromagricultural waste or urban waste.

Goudriaan et al., in “Chemical Engineering Science” (1990), Vol. 45, No.8, pages 2729-2734, describe the process known as HTU or “HydroThermalUpgrading”. Said process allows the conversion of biomass deriving fromplants cultivated for energy purposes (“energy crops”) into liquid fuel(e.g., bio-oil) which comprises treating the biomass in the presence ofwater, at a temperature higher than 300° C., for a time ranging from 5minutes to 15 minutes, at a pressure of 180 bar.

American patent U.S. Pat. No. 7,262,331 describes a process for theproduction in continuous of hydrocarbons having an improved energydensity from biomass, comprising: a first step in which an aqueous feedcontaining biomass, not pre-heated or pre-heated to a temperatureranging from 50° C. to 95° C., is subjected to a treatment whichcomprises bringing said feed in a single step from a pressure of 5 baror lower to a pressure ranging from 100 bar to 250 bar; a secondsubsequent step in which the temperature of the feed under pressure isincreased from 95° C. or less, to 180° C. or over, and the pressurizedfeed is maintained at a temperature not exceeding 280° C. for a periodof up to 60 minutes, thus forming a reaction mixture; a reaction stepwherein the reaction mixture is heated for a period of up to 60 minutesto a temperature higher than 280° C. Said biomass can be selected frommixtures of biomass/water deriving from the aerobic or anaerobicfermentation of industrial or urban waste having a water/biomass ratioranging from 4 to 5. Biomass deriving from agricultural waste or fromdomestic or urban biowaste having a water/biomass ratio ranging from 1to 4, can also be used.

American patent application US 2010/0192457 describes a method forproducing fuel oil which comprises adding an organic solvent to abiomass including lignocellulose, whose humidity content is regulated soas to obtain a total humidity content (i.e., humidity of said organicsolvent+humidity of the biomass) ranging from 10% to 25%, and subjectingthe biomass thus obtained to liquefaction at a temperature ranging from250° C. to 350° C.

Processes are also known for the upgrading of bio-oil to givehydrocarbon cuts to be used in the field of biofuels.

American patent U.S. Pat. No. 5,180,868, for example, describes amulti-step method for the production of gasoline with a high content ofaromatic compounds, comprising the following steps:

-   -   deoxygenating a crude oil comprising hydroxy-aromatic        hydrocarbon compounds containing one or more rings, at a        temperature of 300° C.-450° C. so as to obtain a deoxygenated        oil comprising compounds containing one or more aromatic rings;    -   removing the water from said deoxygenated oil;    -   distilling the deoxygenated oil obtained in order to remove the        compounds containing one aromatic ring such as gasoline and        leaving the compounds containing more aromatic rings;    -   after distillation, subjecting the compounds containing more        aromatic rings to cracking in the presence of hydrogen and of a        bifunctional catalyst so as to obtain a cracked oil, comprising        compounds containing one aromatic ring; and    -   distilling the cracked oil in order to remove the compounds        containing one aromatic ring, such as gasoline.

Said crude oil can derive from the liquefaction of biomass.

American patent application US 2010/0083566 describes a process for thepreparation of a component for bio-gasoline which comprises:

-   -   (I) obtaining at least one bio-oil and, if necessary, subjecting        said bio-oil to liquefaction;    -   (II) feeding the bio-oil in liquid form to a fluid-bed catalytic        cracking reactor (FCC—“Fluid Catalytic Cracking”) together with        at least one mineral oil;    -   (III) subjecting the components fed to said reactor to cracking        so as to obtain at least one fraction of liquefied petroleum gas        (“bio-LPG”—i.e. “bio-Liquefied Petroleum Gas”) and one fraction        of bio-naphtha;    -   (IV) subjecting at least a part of the fraction of liquefied        petroleum gas (bio-LPG) to alkylation or to catalytic        polymerization; and    -   (V) combining at least a part of the product obtained in        step (IV) with at least a part of the bio-naphtha fraction so as        to form a component for bio-gasoline.

Said bio-oil can derive from fish, algae grown in ponds or bioreactors,marine microorganisms or mammals.

American patent application US 2011/0160505 describes a process for thepreparation of hydrocarbons from a feedstock deriving from renewablesources comprising at least one “tall oil” (i.e. by-product of the Kraftproduction process of cellulose pulp), said process comprising:

-   -   a. heating the feedstock deriving from renewable sources        comprising at least one “tall oil” to a temperature ranging from        about 60° C. to about 80° C.;    -   b. bringing the feedstock deriving from renewable sources to a        reaction area, maintaining the temperature at a value ranging        from about 60° C. to about 80° C.;    -   c. treating the feedstock deriving from renewable sources in the        reaction area by means of hydrogenation and deoxygenation in        order to obtain a reaction product comprising paraffins having        from 8 to 24 carbon atoms, and recycling a part of the reaction        product to the reaction area wherein the volume ratio between        the recycled reaction product and the feedstock ranges from        about 2:1 to about 8:1; and    -   d. isomerizing at least a part of the paraffins present in the        reaction product in an isomerization area by contact with an        isomerization catalyst, under isomerization conditions, so as to        isomerize at least a part of the paraffins to branched paraffins        and generate the hydrocarbon product.

International patent application WO 2012/005784 describes a process forthe liquefaction of biomass which comprises combining the biomass with amixture of solvents comprising at least one liquefaction solvent and atleast one make-up solvent in a pressurized reaction container so as toobtain a liquefaction mixture, and heating the liquefaction mixture to atemperature of about 250° C., operating at a pressure of about 200 psi,so as to obtain a crude reaction product comprising liquid bio-oil,wherein the liquefaction solvent has a Hansen interaction radius withconiferyl alcohol lower than 15 MPa^(1/2), and wherein hydrogen ingaseous form is not added.

The bio-oil obtained can be mixed with other refinery streams andsubjected to hydrotreatment stage in order to obtain biofuels.

The above upgrading processes of bio-oil, however, can have somedrawbacks. These processes often presuppose the creation of an upgradingplant specific for bio-oil. Furthermore, the bio-oil is at timessubjected to intermediate purification passages, with an increase in theoverall process cost. In addition, bio-oil is more polar than apetroleum cut, as it contains a residual amount of heteroatoms rangingfrom 10% to 18% by weight with respect to the overall weight of thebio-oil. For this reason, the bio-oil can substantially be only slightlydiluted with refinery hydrocarbon streams and, in general, in order toco-feed it together with said hydrocarbon streams to refinery plantsalready existing, co-solvents with at least a medium polarity are used,capable of facilitating its miscibility with said hydrocarbon streams.This expedient, however, also leads to an increase in the operatingcosts in the refinery plant due to the use of solvents not typicallyhydrocarbon such as those normally used.

The Applicant has faced the problem of finding a process for theproduction of biofuels from solid urban waste which allows the bio-oilobtained from said solid urban waste to be sent directly to a refineryplant, in particular to a hydroconversion section. In particular, theApplicant has faced the problem of finding a process for the productionof biofuel from solid urban waste capable of using the bio-oil obtainedfrom said solid urban waste in a refinery plant normally used for thetreatment of heavy crude oils and residues of sub-atmosphericdistillation.

The Applicant has now found that the production of biofuels from solidurban waste can be advantageously carried out by means of a processwhich comprises subjecting said waste to liquefaction, separating theoily phase consisting of bio-oil and obtained from said liquefaction andsubjecting said oily phase consisting of bio-oil to hydroconversion inslurry phase in the presence of at least one nanodispersed hydrogenationcatalyst. The biofuels thus obtained can be used as such, or mixed withother fuels, for automotive.

Numerous advantages can be obtained with the above process, such as, forexample:

-   -   use of waste biomasses for which there is already a collection        chain;    -   use of biomasses which do not compete with the food cycle and        completion of said cycle allowing a route to valorize its waste;    -   use of biomasses which do not have to be cultivated with        exploitation of agricultural and/or forest surfaces;    -   liquefaction treatment which does not require the use of        catalysts;    -   integration between conversion of a waste biomass into bio-oil        (i.e. liquefaction) with hydroconversion of the same and        subsequent upgrading of the products obtained so as to obtain        biofuels (i.e. bio-diesel, bio-gasoline);    -   sending the bio-oil obtained from liquefaction as such to        hydroconversion without the need for pre-treatments and/or the        addition of solvents;    -   upgrading the products obtained from hydroconversion, which does        not require a plant specifically dedicated for the upgrading of        bio-oil, said treatment being carried out in refinery plants        already operating, in which normal oil cuts are treated;    -   use of the same operative conditions used for upgrading oil cuts        of a fossil origin, with the advantage of not having to        significantly modify refining plants already operating: this        increases the versatility of the refinery section, with positive        repercussions on the refinery margins;    -   possibility of feeding the bio-oil to the hydroconversion        treatment in co-feeding with normal petroleum cuts: this allows        a proportional increase to be obtained, in the amount of        products that can be used in the diesel field (bio-diesel),        thanks to the introduction of a component of a biological        origin;    -   non-use of co-solvents either in the liquefaction phase or in        the upgrading phase.

An object of the present invention therefore relates to an integratedprocess for the production of biofuels from solid urban wastecomprising:

-   -   subjecting said waste to liquefaction obtaining a mixture        comprising an oily phase consisting of bio-oil, a solid phase        and an aqueous phase;    -   subjecting the mixture obtained from said liquefaction to        separation obtaining an oily phase consisting of bio-oil, a        solid phase and an aqueous phase;    -   subjecting the oily phase consisting of bio-oil, obtained from        said separation, to hydroconversion in slurry phase, in the        presence of at least one nano-dispersed hydrogenation catalyst;    -   wherein said liquefaction is carried out at a temperature        ranging from 150° C. to 350° C., preferably ranging from 200° C.        to 320° C., at a pressure ranging from 5 bar to 170 bar,        preferably ranging from 15 bar to 115 bar, and for a time        ranging from 5 minutes to 240 minutes, preferably ranging from        15 minutes to 90 minutes.

For the aim of the present description and of the following claims, thedefinition of the numerical ranges always includes the extremes, unlessotherwise specified.

For the aim of the present description and of the following claims, theterm “biofuels” refers to fuels containing at least one component of abiological origin in a quantity higher than or equal to 0.5% by weightwith respect to the total weight of the fuels contained therein.

For the aim of the present description and of the following claims, theterm “comprising” also includes the terms “essentially consisting of” or“consisting of”.

For the aim of the present description and of the following claims, theterm “nanodispersed” means that the hydrogenation catalyst has anaverage diameter smaller than or equal to 10 nm, preferably ranging from1 nm to 6 nm.

According to a preferred embodiment of the present invention, said solidurban waste can be selected, for example, from:

-   -   the organic fraction of solid urban waste deriving from selected        collection;    -   prunings deriving from the maintenance of public parks;    -   agribusiness waste products and waste products of large        retailers;    -   primary and/or biological sludges produced by urban water        treatment plants;    -   or mixtures thereof. The organic fraction of solid urban waste        deriving from selected collection and primary and/or biological        sludges produced by urban water treatment plants, are preferred.

According to a preferred embodiment of the present invention, said solidurban waste can be treated by subjecting it to a preliminary grinding orsizing process before being liquefied.

According to a preferred embodiment of the present invention, said solidurban waste is wet. Said solid urban waste can preferably have a watercontent higher than or equal to 50% by weight, preferably ranging from55% to 80% by weight, with respect to the total weight of said solidurban waste.

Said liquefaction can be carried out in reactors known in the art, suchas, for example, autoclaves.

Said liquefaction can be carried out operating in various modes such as,for example, batchwise or in continuous.

Considering that the thermal energy necessary in said liquefaction caneither totally or partially derive from the thermal recovery orcombustion of traditional energy vectors, for example methane gas,liquid petroleum gas (LPG), mineral oil, coal, etc., it is not excludedthat the thermal energy can derive from other renewable sources such as,for example, solar sources, or biomasses.

Said separation can be carried out using techniques known in the art,such as, for example, gravity separation (i.e. sedimentation,decanting), filtration, centrifugation. Said separation is preferablycarried out by means of gravity separation.

During said liquefaction a gaseous phase is also formed, equal to about10% by weight-25% by weight with respect to the weight (dry weight) ofsaid solid urban waste. Said gaseous phase is mainly composed of carbondioxide (CO₂) (about 80% in moles-95% in moles) and of a mixture ofhydrocarbons having from 1 to 4 carbon atoms or of other gases (about 5%in moles-20% in moles). This gaseous phase, after separation, separationwhich can be carried out, for example, by depressurization of thepressurized container in which said liquefaction is carried out beforesending the mixture (oily phase+solid phase+aqueous phase) obtained insaid liquefaction to separation, is generally sent to further treatmentsin order to upgrade its organic fuel component.

The solid phase obtained after separation generally comprises ashes andinert materials. Said solid phase can be used, for example, as startinginorganic material in the building industry, or in the ceramic industry.

The aqueous phase obtained after separation comprises part of theorganic material included in said solid urban waste. Said aqueous phasecan generally have a content of organic material higher than or equal to25% by weight, preferably ranging from 30% to 50% by weight, withrespect to the total weight of the dry fraction of said solid urbanwaste. Said aqueous phase can be subjected to further treatments suchas, for example, biological treatments, before being disposed of.

Bio-oil can be produced from said liquefaction, with an overall yieldranging from 15% to 50%, said yield being calculated with respect to theweight of the dry fraction of the initial solid urban waste.

Alternatively, in order to increase the yield of bio-oil (i.e. anincrease in yield ranging from 5% to 30%, said increase in yield beingcalculated with respect to the weight of the dry fraction of the initialsolid urban waste), said aqueous phase can be recycled to saidliquefaction.

In this respect, said aqueous phase can be subjected to fermentation inthe presence of at least one oleaginous yeast obtaining a biomass whichcan be subjected to said liquefaction as described, for example, ininternational patent application WO 2011/030196 in the name of theApplicant; or, said aqueous phase can be subjected to treatment with atleast one adsorbing material obtaining a further aqueous phase which canbe subjected to fermentation in the presence of at least one oleaginousyeast obtaining a biomass which can be subjected to said liquefaction asdescribed, for example, in international patent application WO2011/128741 in the name of the Applicant; or, said aqueous phase can besent back to aerobic treatment, for example, to a water purificationplant as described, for example, in international patent application WO2011/117319 in the name of the Applicant.

According to a preferred embodiment of the present invention, said oilyphase consisting of bio-oil can be subjected to hydroconversion togetherwith heavy oils of a fossil origin such as, for example, heavy crudeoils, bitumens deriving from tar sands, distillation residues, heavyresidues deriving from thermal treatment processes, oils deriving fromcoal, oil shales.

According to a preferred embodiment of the present invention, said oilyphase consisting of bio-oil and said heavy oils of a fossil origin canbe used in a weight ratio ranging from 0.01 to 50, preferably rangingfrom 0.1 to 10.

It should be noted that, for the aim of the present invention, saidhydroconversion can be carried out by means of the EST technology (EniSlurry Technology) described in detail in the following Italian patentapplications: MI95A001095, MI2001A001438, MI2002A002713, MI2003A000692,MI2003A000693, MI2003A002207, MI2004A002445, MI2004A002446,MI2006A001512, MI2006A001511, MI2007A001302, MI2007A001303,MI2007A001044, MI2007A001045, MI2007A001198, MI2008A001061.

The EST technology, in fact, allows a wide versatility with respect tothe hydrocarbon feedstock (i.e. to the hydrocarbon materials subjectedto hydroconversion), allowing the conversion of a wide type ofhydrocarbon materials, among which heavy crude oils, bitumens derivingfrom tar sands, distillation residues, heavy residues from thermaltreatment processes, oils from coal and oil shales. As mentioned in theabove Italian patent applications, the hydroconversion is carried out inthe presence of at least one hydrogenation catalyst which preferablyconsists of sulfides of transition metals, more preferably molybdenum(Mo), tungsten (W), nickel (Ni), cobalt (Co), ruthenium (Ru), iron (Fe),chrome (Cr): among these transition metals, molybdenum (Mo) and tungsten(W) show the most satisfactory performances. Said nanodispersedhydrogenation catalyst can also be introduced as oil-soluble precursormixed with the hydrocarbon feedstock: in this case, the active form ofthe nanodispersed hydrogenation catalyst is formed in situ by means ofthermal decomposition of the precursor in the reaction environment. Thehydrocarbon feedstock is preferably sent to the reaction section which,as specified in the above Italian patent applications, generallyconsists of one or more bubble columns, together with a stream ofhydrogen or a stream consisting of a mixture of hydrogen/hydrogensulfide (H₂S), operating under the following conditions: temperaturepreferably ranging from 350° C. to 480° C., pressure preferably rangingfrom 100 bar to 200 bar, average residence time preferably ranging from2 hours to 6 hours. At the end of the hydroconversion the followingproducts are obtained:

-   -   gaseous products, i.e. fuel gas and liquid petroleum gas (LPG)        which are used as such as fuels;    -   liquid products, i.e. naphtha, atmospheric gas oil (AGO) and        vacuum gas oil (VGO) which are sent to separation and,        subsequently, to upgrading so as to obtain fuels for automotive        (i.e. diesel, gasoline);    -   a fraction of heavier products (500+° C.) (i.e. non-converted        products) which also contains the nanodispersed hydrogenation        catalyst, together with the small fraction of coke optionally        formed and sulfides of the metals present in the hydrocarbon        feedstock itself, which is recycled (i.e. recycled stream) to        the hydroconversion to which it is fed together with the fresh        hydrocarbon feedstock.

In order to keep the concentration of solids present in the systemconstant, a blow down is preferably applied: the entity of said blowdown depends on the severity of the operating conditions and on the typeof hydrocarbon feedstock used. In this way, an aliquot of the catalystis also removed, which must be reintegrated, by means of make-upcatalyst, introduced together with the fresh hydrocarbon feedstock.

According to a preferred embodiment of the present invention, saidhydroconversion can be carried out in the presence of a hydrogen streamor of a stream consisting of a mixture of hydrogen/hydrogen sulfide(H₂S).

According to a preferred embodiment of the present invention, saidnanodispersed hydrogenation catalyst can be selected from sulfides oftransition metals such as, for example, molybdenum sulfide (MoS₂),tungsten sulfide (WS₂), or mixtures thereof, or an oil-soluble precursorof the same.

According to a preferred embodiment of the present invention, saidhydrogenation catalyst can be used in such as quantity that theconcentration of transition metal present in the oily phase consistingof bio-oil, or in the oily phase consisting of bio-oil together withheavy oils of a fossil origin, can range from 50 wppm to 50000 wppm,preferably from 100 wppm to 30000 wppm (wppm=“weight part per million”).

A co-catalyst can be optionally used together with said hydrogenationcatalyst, having particles with nanometric or micrometric dimensions,which can be selected from cracking and/or denitrogenation catalystssuch as, for example, zeolites having small-dimensioned crystals andwith a low aggregation degree between the primary particles, oxides,sulfides or precursors of nickel (Ni) and/or cobalt (Co), in a mixturewith molybdenum (Mo) and/or tungsten (W): further details relating tothe use of said co-catalyst can be found, for example, in Italian patentapplication MI2008A001061 indicated above.

According to a preferred embodiment of the present invention, saidhydroconversion can be carried out at a temperature ranging from 350° C.to 480° C., preferably ranging from 380° C. to 450° C.

According to a preferred embodiment of the present invention, saidhydroconversion can be carried out at a pressure ranging from 100 bar to200 bar, preferably ranging from 120 bar to 180 bar.

According to a preferred embodiment of the present invention, saidhydroconversion can be carried out with an average residence timeranging from 2 hours to 8 hours, preferably ranging from 3 hours to 6hours.

Said hydroconversion can be carried out in one or more reactor(s) inseries selected from hydroconversion reactors in slurry phase previouslydescribed in the Italian patent applications indicated above.

At the end of said hydroconversion, the following products are obtained:

-   -   gaseous products, i.e. fuel gas and liquid petroleum gas (LPG)        which are used as such as fuels;    -   liquid products, i.e. naphtha, atmospheric gas oil (AGO) and        vacuum gas oil (VGO) which are sent to separation and,        subsequently, to upgrading so as to obtain biofuels for        automotive (i.e. bio-diesel, bio-gasoline);    -   a fraction of heavier products (500+° C.) (i.e. non-converted        products) which also contains the nanodispersed hydrogenation        catalyst, together with the small fraction of coke optionally        formed and sulfides of the metals present in the hydrocarbon        feedstock itself (i.e. oily phase consisting of bio-oil or oily        phase consisting of bio-oil together with heavy oils of a fossil        origin), which is recycled (i.e. recycled stream), after blow        down, to the hydroconversion to which it is fed together with        the fresh hydrocarbon feedstock and make-up catalyst.

The separation of said liquid products can be carried out by means ofprocesses known in the art such as, for example, flash separation,distillation, gravity separation.

Said upgrading can be carried out by means of processes known in the artsuch as, for example, cracking, hydrogenation, hydrocracking, in orderto obtain biofuels for automotive (i.e. bio-diesel, bio-gasoline).

The present invention will now be illustrated by means of an embodimentwith reference to FIG. 1 provided hereunder.

According to a typical embodiment of the process object of the presentinvention, the solid urban waste (e.g., sludges deriving from an urbanwastewater treatment plant) (Stream 1) is subjected to liquefactionobtaining: a mixture (not represented in FIG. 1) including three phases,i.e. an oily phase consisting of bio-oil, a solid phase (i.e. residue)and an aqueous phase; and, as already indicated above, a gaseous phase.Said mixture is sent to a separation section of phases (not representedin FIG. 1) in order to separate the above three phases obtaining: anoily phase consisting of bio-oil (Stream 2), a solid phase (i.e.residue) (Stream 7) comprising ashes, inert products, which can be used,for example, as starting inorganic material in the building industry, orin the ceramic industry, and an aqueous phase (Stream 6) which can besubjected to further treatments such as, for example, biologicaltreatments, before being disposed of, or it can be subjected to optionaladsorption with at least one adsorbing material and subsequentfermentation in the presence of at least on oleaginous yeast, obtaininga biomass which can be subjected to said liquefaction together with saidsolid urban waste (Stream 1) (not represented in FIG. 1) as describedabove.

As described above, during the liquefaction, a gaseous phase (Stream 5)comprising carbon dioxide (CO₂), gaseous hydrocarbons having from 1 to 4carbon atoms, or other gases, is also produced, which can be separated,for example, by depressurization of the pressurized recipient in whichsaid liquefaction is carried out before sending the mixture (oily phaseconsisting of bio-oil+solid phase+aqueous phase) obtained afterliquefaction to the separation section of phases. The gaseous phase thusobtained (Stream 5) can be sent to further treatments for upgrading itsorganic fuel component.

Said oily phase consisting of bio-oil (Stream 2) is added with arefinery hydrocarbon feedstock (Stream 3) and the mixture obtained(Stream 4) is sent to hydroconversion in the presence of a nanodispersedhydrogenation catalyst [e.g., a catalyst based on molybdenum (MoS₂)],obtaining a reaction effluent (Stream 8) which is sent to separation[e.g., flash separation, distillation] (not represented in FIG. 1)obtaining:

-   -   gaseous products (Stream 9), i.e. fuel gas and liquid petroleum        gas (LPG) which are recovered and used as such as fuels;    -   liquid products (Stream 10), i.e. naphtha, atmospheric gas oil        (AGO) and vacuum gas oil (VGO) which are sent to separation (not        represented in FIG. 1) and, subsequently, to upgrading (e.g., by        means of hydrogenation), so as to obtain bio-fuels for        automotive (i.e. bio-diesel, bio-gasoline) (Stream 12);    -   a fraction of heavier products (500+° C.) (i.e. non-converted        products) (Stream 11) which also contains the nanodispersed        hydrogenation catalyst, together with the small fraction of coke        optionally formed and sulfides of the metals present in the        hydrocarbon feedstock itself (Stream 4), which is recycled (i.e.        recycled stream (Stream 14), after blow down (Stream 13), to        hydroconversion to which a new fresh hydrocarbon feedstock and        make-up catalyst are also fed (not represented in FIG. 1).

Alternatively, said oily phase consisting of bio-oil (Stream 2) can besent, as such, to hydroconversion (not represented in FIG. 1).

Some illustrative and non-limiting examples are provided for a betterunderstanding of the present invention and for its practical embodiment.

Example 1

500 g of sludges deriving from an urban wastewater treatment plant(clean and dirty water cycle, rain water) were fed, by means of asuitable dosage system, into a 1 litre stirred autoclave. The dry weightof said sludges was equal to 30% by weight (150 g).

After creating an inert atmosphere inside the autoclave by washings withnitrogen, the autoclave was rapidly heated so as to reach an internaltemperature of 310° C.: the whole was kept under these conditions for 1hr, under stirring, and it was observed that the internal pressure ofthe autoclave reached the maximum pressure of 110 bar.

The autoclave was then rapidly cooled to 80° C. and the gaseous phasewas separated. Said gaseous phase was analyzed separately by means ofgas-chromatographic techniques and proved to be equal to about 12 g (8%by weight of the initial dry weight). The analysis showed that thegaseous phase consisted for 90% of carbon dioxide (CO₂).

The reaction raw product thus obtained was separated under heat in agravitational separator, obtaining three phases:

-   -   an oily phase consisting of bio-oil which, once anhydrified,        proved to be equal to 43.5 g (29% by weight of the initial dry        weight);    -   a solid phase consisting of a solid residue equal to 75 g (50%        by weight of the initial dry weight);    -   an aqueous phase equal to 360 g having a sludges content of 19.5        g (13% by weight of the initial dry weight).

Said oily phase consisting of bio-oil (hereinafter indicated as“bio-oil”) whose characteristics are specified in Table 1, was subjectedto hydroconversion.

The following products were also subjected to hydroconversion:

-   -   a vacuum residue (VR) of a Caucasus origin (Ural) (hereinafter        indicated as “Ural VR”) (reference test) whose characteristics        are specified in Table 1;    -   a mixture of bio-oil/Ural VR (weight ratio 25/75).

For this aim, the hydroconversion was carried out in a laboratory plantwith a reactor having a total volume of 40 cm³. The catalyst and thehydrocarbon feedstock (i.e. the oily phase consisting of bio-oil, orUral VR, or the mixture of bio-oil/Ural VR) were introduced into thereactor at the beginning of the test. The reactor was subsequentlybrought to the temperature value and under a hydrogen pressure: saidoperative conditions were kept constant for the whole duration of thetest. The three hydroconversion tests were carried out under thefollowing operative conditions:

-   -   hydrocarbon feedstock treated: 10 g;    -   catalyst used: nanodispersed molybdenum sulfide (MoS₂);    -   molybdenum (Mo) concentration: 3000 wppm;    -   operative pressure: 160 bar;    -   reaction temperature: 430° C.;    -   residence time: 5 hrs.

The products obtained from the hydroconversion were characterized: thedata obtained are reported in Table 2.

TABLE 1 BIO-OIL URAL VR CHARACTERISTICS STANDARD (% weight) (% weight)Distillation ASTM D2887-08 IBP (170° C.) 0.3 — 170° C.-300° C. 16.8 0.2350° C.-500° C. 28.5 6.4 500+° C. 42.5 93.0 Sulfur EN ISO 20846:20110.75 3.07 Nitrogen ASTM D5291-10 5.82 0.59

TABLE 2 BIO-OIL/URAL BIO-OIL CHARACTERISTICS STANDARD URAL VR (% w) VR(% w) (% w) H₂S⁽¹⁾ — 1.3 0.1 — GAS⁽¹⁾ — 3.7 3.5 4.9 (C₁-C₄) DISTILLATIONASTM D2887-08 IBP (170° C.) 7.8 8.4 5.8 170° C.-300° C. 41.3 48.0 64.7350° C.-500° C. 30.7 29.8 17.3 500+° C. 17.2 15.6 5.8 Solid productsformed — 1.4 1.6 3.2 (2) (THFi) ⁽¹⁾determined throughgas-chromatographic techniques; (2): insoluble in tetrahydrofuran.

From the data reported in Table 2, it can be seen that bio-oil, as such,or mixed with Ural VR, can be subjected to hydroconversion operatingunder the same operative conditions used in the case of Ural VR, withoutnegatively influencing the formation of the final products (i.e.biofuels or fuels).

Example 2

A reference plant was used for the treatment of urban wastewater (cleanand dirty water cycle, rain water) which treats 100 million m³/year ofwastewater. The wastewater was subjected to pre-treatment by passingthrough the screening, sand removal and de-oiling sections, obtaining anaqueous phase which was sent to wastewater treatment, obtaining sludgesand purified water for irrigation. The sludges obtained from theabove-mentioned treatment (aerobic bacterial oxidation) were collected,obtaining 46000 tons/year of sludges (32% dry content).

The 46000 tons/year of wet sludges were sent, in continuous, toliquefaction, i.e. to a tubular reactor. The liquefaction was carriedout at 310° C. (internal temperature of the reactor), at 110 bar(internal pressure of the reactor), for about 1 hour.

The reaction raw product was separated, in continuous, in agravitational separator, obtaining the following phases:

-   -   an aqueous phase (31000 tons/year), which was sent directly to        said urban wastewater treatment plant and which proved to be        equal to 0.03% by volume with respect to the total volume of        wastewater treated in said treatment plant (this did not cause        any variation in the performances of said treatment plant, as        water was obtained, which completely fell within the        specifications required by law);    -   a solid phase consisting of a solid residue (7910 tons/year)        which was sent to a thermovalorization;    -   an oily phase consisting of bio-oil (4416 tons/year);    -   a gaseous phase sent to energy recovery on the basis of its        residual calorific power.

The oily phase consisting of bio-oil, without any particularpre-treatment, was sent to a refinery hydroconversion section in slurryphase of heavy crude oils operating with the EST technology (Eni SlurryTechnology), having a capacity equal to 44000 tons/year, in co-feedingwith Ural VR in a ratio of 1/9. The hydroconversion process in slurryphase was carried out in the presence of hydrogen (H₂), under thefollowing operative conditions:

-   -   catalyst used: nanodispersed molybdenum sulfide (MoS₂);    -   concentration of molybdenum (Mo): 3000 wppm;    -   operative pressure: 160 bar;    -   reaction temperature: 430° C.;    -   residence time: 4 hours.

The reaction effluent was sent to the separation section, obtaining:

-   -   gaseous products, i.e. fuel gas and liquid petroleum gas (LPG)        which are used as such as fuels;    -   liquid products, i.e. naphtha, atmospheric gas oil (AGO) and        vacuum gas oil (VGO) which are sent to separation and        subsequently to upgrading by means of hydrogenation, so as to        obtain biofuels for automotive (i.e. bio-diesel, bio-gasoline);    -   a fraction of heavier products (500+° C.) (i.e. non-converted        products) which also contains the nanodispersed hydrogenation        catalyst, together with the small fraction of coke optionally        formed and sulfides of the metals present in the hydrocarbon        feedstock itself (i.e. oily phase consisting of bio-oil+Ural        VR), which is recycled, after blow down, to hydroconversion to        which a new fresh hydrocarbon feedstock and make-up catalyst are        also fed.

A reference test was also carried out, by feeding only Ural VR to thehydroconversion section in slurry phase.

The yields of the products obtained (%) are reported in Table 3.

TABLE 3 BIO-OIL/URAL VR PRODUCTS (%) URAL VR FG 5.6 5.7 LPG 3.1 2.4Naphtha 5.5 5.7 Diesel 44.8 43.4 VGO 39.1 41.0

From the data reported in Table 3, it can be seen that the bio-oil usedin a mixture with Ural VR can be subjected to hydroconversion, operatingunder the same operative conditions used in the case of Ural VR, withoutnegatively influencing the formation of the final products (i.e.biofuels or fuels).

1. An integrated process for the production of biofuels from solid urbanwaste which comprises: subjecting said waste to liquefaction obtaining amixture comprising an oily phase consisting of bio-oil, a solid phaseand an aqueous phase; subjecting the mixture obtained from saidliquefaction to separation obtaining an oily phase consisting ofbio-oil, a solid phase and an aqueous phase; and subjecting the oilyphase consisting of bio-oil obtained from said separation tohydroconversion in slurry phase, in the presence of at least onenanodispersed hydrogenation catalyst; wherein said liquefaction iscarried out at a temperature ranging from 150° C. to 350° C., at apressure ranging from 5 bar to 170 bar, and for a time ranging from 5minutes to 240 minutes.
 2. The integrated process for the production ofbiofuels from solid urban waste according to claim 1, wherein said solidurban waste is selected from: the organic fraction of solid urban wastederiving from selected collection; prunings deriving from themaintenance of public parks; agribusiness waste products and wasteproducts of large retailers; primary and/or biological sludges producedby urban water treatment plants; or mixtures thereof.
 3. The integratedprocess for the production of biofuels from solid urban waste accordingto claim 1, wherein said solid urban waste is treated by subjecting itto a preliminary grinding or sizing process before being subjected tosaid liquefaction.
 4. The integrated process for the production ofbiofuels from solid urban waste according to claim 1, wherein said solidurban waste is wet.
 5. The integrated process for the production ofbiofuels from solid urban waste according to claim 4, wherein said solidurban waste has a water content higher than or equal to 50% by weightwith respect to the total weight of said solid urban waste.
 6. Theintegrated process for the production of biofuels from solid urban wasteaccording to claim 5, wherein said solid urban waste has a water contentranging from 55% by weight to 80% by weight with respect to the totalweight of said solid urban waste.
 7. The integrated process for theproduction of biofuels from solid urban waste according to claim 1,wherein said oily phase consisting of bio-oil is subjected tohydroconversion together with heavy oils of a fossil origin such asheavy crude oils, bitumens deriving from tar sands, distillationresidues, heavy residues deriving from thermal treatment processes, oilsderiving from coal, oil shales.
 8. The integrated process for theproduction of biofuels from solid urban waste according to claim 7,wherein said oily phase consisting of bio-oil and said heavy oils of afossil origin are used in a weight ratio ranging from 0.01 to
 50. 9. Theintegrated process for the production of biofuels from solid urban wasteaccording to claim 1, wherein said hydroconversion is carried out in thepresence of a stream of hydrogen or of a stream consisting of a mixtureof hydrogen/hydrogen sulfide (H₂S).
 10. The integrated process for theproduction of biofuels from solid urban waste according to claim 1,wherein said nanodispersed hydrogenation catalyst is selected fromsulfides of transition metals, or an oil-soluble precursor of the same.11. The integrated process for the production of biofuels from solidurban waste according to claim 1, wherein said hydrogenation catalyst isused in such a quantity that the concentration of transition metalpresent in the oily phase consisting of bio-oil, or in the oily phaseconsisting of bio-oil together with heavy oils of a fossil origin,ranges from 50 wppm to 50000 wppm.
 12. The integrated process for theproduction of biofuels from solid urban waste according to claim 1,wherein said hydroconversion is carried out at a temperature rangingfrom 350° C. to 480° C.
 13. The integrated process for the production ofbiofuels from solid urban waste according to claim 1, wherein saidhydroconversion is carried out at a pressure ranging from 100 bar to 200bar.
 14. The integrated process for the production of biofuels fromsolid urban waste according to claim 1, wherein said hydroconversion iscarried out with an average residence time ranging from 2 hours to 8hours.